/*

 * Licensed to the Apache Software Foundation (ASF) under one

 * or more contributor license agreements.  See the NOTICE file

 * distributed with this work for additional information

 * regarding copyright ownership.  The ASF licenses this file

 * to you under the Apache License, Version 2.0 (the

 * "License"); you may not use this file except in compliance

 * with the License.  You may obtain a copy of the License at

 *

 *     http://www.apache.org/licenses/LICENSE-2.0

 *

 * Unless required by applicable law or agreed to in writing, software

 * distributed under the License is distributed on an "AS IS" BASIS,

 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

 * See the License for the specific language governing permissions and

 * limitations under the License.

 */

package com.bff.gaia.unified.sdk.io.kinesis;



import com.bff.gaia.unified.sdk.io.UnboundedSource;

import com.bff.gaia.unified.vendor.guava.com.google.common.collect.ImmutableList;



import java.io.IOException;

import java.io.Serializable;

import java.util.Iterator;

import java.util.List;



import static com.bff.gaia.unified.vendor.guava.com.google.common.collect.Lists.newArrayList;

import static com.bff.gaia.unified.vendor.guava.com.google.common.collect.Lists.partition;



/**

 * Checkpoint representing a total progress in a set of shards in single stream. The set of shards

 * covered by {@link KinesisReaderCheckpoint} may or may not be equal to set of all shards present

 * in the stream. This class is immutable.

 */

class KinesisReaderCheckpoint

    implements Iterable<ShardCheckpoint>, UnboundedSource.CheckpointMark, Serializable {



  private final List<ShardCheckpoint> shardCheckpoints;



  public KinesisReaderCheckpoint(Iterable<ShardCheckpoint> shardCheckpoints) {

    this.shardCheckpoints = ImmutableList.copyOf(shardCheckpoints);

  }



  /**

   * Splits given multi-shard checkpoint into partitions of approximately equal size.

   *

   * @param desiredNumSplits - upper limit for number of partitions to generate.

   * @return list of checkpoints covering consecutive partitions of current checkpoint.

   */

  public List<KinesisReaderCheckpoint> splitInto(int desiredNumSplits) {

    int partitionSize = divideAndRoundUp(shardCheckpoints.size(), desiredNumSplits);



    List<KinesisReaderCheckpoint> checkpoints = newArrayList();

    for (List<ShardCheckpoint> shardPartition : partition(shardCheckpoints, partitionSize)) {

      checkpoints.add(new KinesisReaderCheckpoint(shardPartition));

    }

    return checkpoints;

  }



  private int divideAndRoundUp(int nominator, int denominator) {

    return (nominator + denominator - 1) / denominator;

  }



  @Override

  public void finalizeCheckpoint() throws IOException {}



  @Override

  public String toString() {

    return shardCheckpoints.toString();

  }



  @Override

  public Iterator<ShardCheckpoint> iterator() {

    return shardCheckpoints.iterator();

  }

}